Logo link to homepage

Report on Lokon-Empung (Indonesia) — October 2003

Bulletin of the Global Volcanism Network, vol. 28, no. 10 (October 2003)
Managing Editor: Edward Venzke.

Lokon-Empung (Indonesia) Small gas plume; high but variable shallow volcanic seismicity

Please cite this report as:

Global Volcanism Program, 2003. Report on Lokon-Empung (Indonesia). In: Venzke, E. (ed.), Bulletin of the Global Volcanism Network, 28:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200310-266100.

Volcano Profile |  Complete Bulletin


Lokon-Empung

Indonesia

1.358°N, 124.792°E; summit elev. 1580 m

All times are local (unless otherwise noted)


The hazard status at Lokon-Empung throughout the report period of 2 June-19 October was at Alert Level 2 (on a scale of 1-4). Between 2 June and 5 October a white gas plume consistently rose 25-50 m above Tompaluan crater. The gas plume rose slightly higher, to 75 m, during the following two weeks. Seismicity remained above normal background levels during this time, with some variation (table 7). Shallow volcanic earthquakes increased in late July, but by September the weekly count was lower than in early July, eventually reaching a low the week of 15-21 September when no such events were detected. Seismicity quickly returned to high values of 138-209 shallow events per week in October.

Table 7. Seismicity at Lokon-Empung, 2 June-19 October 2003. Data was not available for 16-29 June and 04-31 August. Courtesy of VSI.

Date Deep volcanic (A-type) Shallow volcanic (B-type) Tectonic
02 Jun-08 Jun 2003 13 45 20
09 Jun-15 Jun 2003 25 88 27
30 Jun-06 Jul 2003 18 81 19
07 Jul-13 Jul 2003 17 48 15
14 Jul-20 Jul 2003 9 91 19
21 Jul-27 Jul 2003 25 232 21
28 Jul-03 Aug 2003 16 157 10
01 Sep-07 Sep 2003 11 44 11
08 Sep-14 Sep 2003 7 36 20
15 Sep-21 Sep 2003 12 0 22
22 Sep-28 Sep 2003 34 22 20
29 Sep-05 Oct 2003 33 209 24
06 Oct-12 Oct 2003 5 159 14
13 Oct-19 Oct 2003 24 138 14

Geologic Background. The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2 km apart), has a flat, craterless top. The morphologically younger Empung volcano to the NE has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred. A ridge extending WNW from Lokon includes Tatawiran and Tetempangan peak, 3 km away.

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).